The present invention relates generally to failure repairs for electronic systems. More specifically, the invention provides a method and system for repairing hard failures in the field. Merely by way of example, the invention has been applied to integrated circuits such as field-programmable gate arrays (FPGAs), but it would be recognized that the invention has a much broader range of applicability.
Integrated circuits (ICs) usually include millions of devices. The large number of devices has significantly improved circuit complexity. Additionally, the feature size of the smallest devices has been reduced in order to improve circuit density. High circuit complexity and density can enhance IC performance, but have also posed significant challenges to quality and reliability control.
To improve circuit quality, ICs are usually tested prior to packaging. One type of IC is FPGAs. Faults related to FPGAs can be detected by a Built-In Self-Test (BIST). Upon fault identifications, laser beams may be used to change connection status of certain fuses or anti-fuses, and thus activate redundancy devices in order to replace defective devices. But the laser beams are usually difficult to maintain and to operate.
After ICs have been put into use, certain tests are also performed to monitor the circuit performance. For example, error correction codes (ECCs) can be used to identify soft errors. Soft errors usually result from neutron or alpha particle radiation. Upon detections of soft errors, certain programmable logic elements are reprogrammed according to the desired configuration. Error correction codes by themselves cannot effectively repair hard failures.
Hence it is desirable to improve techniques for repairing hard failures.